Lithium v what ever, or where the posts get moved to :lol:

[jon_d]

Brian,

what size A/C do you have. I'm trying to work out what size to fit to the Bedford.

thanks,

jd

[Dot]

What happens in the middle of winter and not much sun around?

[Mrcoolabah1au]

Think I read some were he had a 5 Kva

[homeless]

Aircon is only a small Mitsubishi I think it is the smallest but I only have a small bus.

Regards
Brian

[Jon and Kay]

Brian, I need some clarification as I prepare for the new batteries somewhere up the track.
I also run convection/microwave, bread makers, 240v fridge, everything on standby, never turned off. I have 600ah of AGMs and 700watt solar. I can also run the aircon (provided I start it on Genny first as inverter too small) My system is usually on float by middle of each day.
I wonder if your experience is as much a properly sized system, rather than Lithium vs AGM?
I see great benefits with Lithium, I will use them next time, but because they are lighter and faster charging, not because I think they are magical.
As I read other RV experiences, it appears to me they are experiencing great results because they have installed the right size for their purpose, for the first time, having endured too small a system in the past, but could have achieved similar results whatever battery chemistry they chose.

[slowhand]

G'day Jon and Kay, can't tell you about on the road with lifepo4, as I'm about to install 400ah in the next week or so when they arrive.

The property I purchased here in Tas this year had 2kw solar and 1000ah agm. The house runs on 12v and has done for the last 20+ years, according to the previous owners they had to change their batteries every 5-6 years and always struggled with energy, particularly on cloudy days.

My kids delivered me 640AH of lifepo4 to try out and the result has been dramatic, 2-4 cloudy days and I still have about 50% SOC. In the 4 months I've used them, have decided to change the house to 240v (already wired) because I never run out of power. It's not magic. It has to do with density, ability to accept charge/discharge rates and access to the stored energy compared to LA. Will be upgrading to 1000ah later this year, then will be on easy street, with no bills.

The trick I've learned is in what they are connected with, some use braided wire connections and even heard of those using aluminum bar connections, which makes no sense at all. I use 3mm x 18mm and 25mm copper bar, which means I can draw huge amounts of energy if needed and the pack will take in as much as can be produced, unlike LA which dribbles it in with great loses. This also keeps the pack tight together and secure, so you don't get any vibration which over time effects braided connections.

I currently have 400ah of gel and 460w solar in my bus and hate them, it's about to become 910w solar and 400ah lifepo4. Backed up with a 60 amp dc-dc charger and a new paint job, currently under way. Was going traveling this month, but have to many things to do, including committing to helping new friends instill their own lifepo4 systems. At least I get free beer.

I may be wrong, but with 400ah lifepo4, you get to use 80% of the energy, compared to LA which in reality is below 50% of usable energy.

As for prices, my kids import and build lifepo4 systems. They are builders in a semi rural area of Vic and put them their own constructions and after market setups.

Drop me a line if at some time you are looking at changing and can tell you what current prices are for cells from 40ah-100ah. They are much lower than what are advertised and if you set them up yourself, even cheaper.

I'm no techie, so Terry is the one to listen to in that regard, what I say comes from my kids and what I've learnt from playing with them. Which isn't much as my youngest daughter is constantly updating me on new developments and techniques, most goes over my head. Now i've got to learn to program the BMS, so have started a steep learning curve in linux programming and software writing. Then can do it all myself and as I'm retired, (sort of) have the time to muck round. Living by oneself has lots of advantages I've found.

[Jon and Kay]

I currently have 400ah of gel and 460w solar in my bus and hate them, it's about to become 910w solar and 400ah lifepo4

That is exactly my point. I had 600ah AGM and 500watt solar and hated them too, but increased solar to 700 watt and they are great. You are upgrading to Litium, a good choice, but if you had just increased your solar and retained the AGMs I believe you would have been a happy camper that way too.

[slowhand]

I currently have 400ah of gel and 460w solar in my bus and hate them, it's about to become 910w solar and 400ah lifepo4

That is exactly my point. I had 600ah AGM and 500watt solar and hated them too, but increased solar to 700 watt and they are great. You are upgrading to Litium, a good choice, but if you had just increased your solar and retained the AGMs I believe you would have been a happy camper that way too.

You may have missed my point, I had 2kw of solar and 1000ah of LA, which couldn't cope with running the house unless it was sunny most every day. By dropping my storage capacity to 640ah lifepo4, I now have enough energy to run the house for days. When it's upgraded to 1000ah, will use a portable A/C on hot days

It's deoends in what you want, hate being somewhere in a lovely setting and having to be conservative with energy, constantly checking my power supply. Since switching to lifepo4 at home, stopped watching the system and am adding more and more things to use. Have 3-6kw pure sine wave inverter and am purchasing another as a backup, the house will be fuly 240v as soon as it arrives. Already ordered 240v LEDs and other goodies.

Now use toasters, induction hotplates, vacum cleaner, washing machine, pc, previously they were run via a generator and new 55inch led tv and I am a very happy camper. Plus charge all my little batteries and am changing them to lifepo4, have some AA I'm trying out and so far they out perform the others by 2 days of full use.

The major differences are with lifepo4, fast recharge, more capacity to use, lightness, longevity and the ability to have full control over your energy system. If you do the economies of scale, you find lifepo4 compared to LA for longevity, capacity and usability, are dirt cheap.

Like Martin, adding more panels to the bus so I can be much more comfortable, watch TV all day if I want, A/C, cook and cool the beer. With my gel batteries, there's no way I can heat water or use A/C, because with the gel and AGM, you don't have the usable capacity to do that. Approximately 40-50% of your LA energy storage is below 12v, with lifepo4, you have at least 80% and if you want 100% above 12v.

That's me for the day, have to go push a lot of soil the council has dumped here for me. They are doing roadside cleanup and widening, the soil is beautiful and rich, so jokingly suggested they could dump it here if they want and this week they have dropped over 40 x 10m truck loads. Have piles of clay and rocks to fill in a gully or two and piles of topsoil for the gardens.

Have a lovely day everyone.

[dapope]

Enjoy pushing the dirt Slowhand!

[T1 Terry]

Hi folks, sorry there was no scintillating chapter last night, the internet died for some reason but it's back up today.

I currently have 400ah of gel and 460w solar in my bus and hate them, it's about to become 910w solar and 400ah lifepo4

That is exactly my point. I had 600ah AGM and 500watt solar and hated them too, but increased solar to 700 watt and they are great. You are upgrading to Lithium, a good choice, but if you had just increased your solar and retained the AGMs I believe you would have been a happy camper that way too.

Let's look at this example, 600Ah agm will provide 300Ah at a C20 rate, or 5amps per 100Ah of capacity, in this case 30 amp max load if you want the 300Ah without dropping below the magic 50% SOC where the terminal voltage under load drops below 12v.
Reading through this information from Trojan http://www.trojanbattery.com/tech-suppo ... intenance/ they recommend a max charging rate of 13% of the C20 rated capacity, in this case 600Ah x 0.13 = 78 amps, fairly good but only due to the capacity, a 100Ah battery would have a charger recommendation of only 13 amps.
So, 500w of solar x 70% max expected harvest rate = 350w, lead acid required 20% more when recharging to replace what was used, so 350w x 5 peak sun hrs = 1750w or 145Ah @ 12v at best. Allowing for the 20% inefficiency in recharging lead acid batteries the limited replaceable capacity was 120Ah max, any more and the battery would not fully recharge and it relied on the fully 5 peak sun hrs each day to achieve that.
Now add in the issue of the tapering charge rate to get the battery from 80% SOC to 100% SOC, so not all of the sun hrs can be at their peak possible charging rate, this means that 120Ah that can be replace to return to a 100% SOC would really be more likely to be around 100Ah.
In all fairness to the comparison it's doubtful the batteries ever returned to the 100%SOC, a system in use can not be returned to 100% SOC by solar only unless the solar system is massively over sized.

Let's look at the same system using only 400Ah of lithium:
Max discharge rate to get that 400Ah capacity = 3C or 1200 amps, rather unlikely in a motorhome so let's just say there is no limit to normal use
Charge efficiency = 100% if you look at it in Ah figures. This will get the flame wars started if the motor mouths don't put their brains into gear and allow for the fact the charging voltage is higher than the discharge voltage, so although the watts out is less than the watts in, the Ah out = the Ah in required. In other words, if you used 145Ah you only required 145Ah to replace it.
Charge rate acceptance = This is the same as the discharge rate, 3C, so again a max possible of 1200amps, so as far as a house system we might as well say it is also unlimited.
So, the example 500w of solar x 70% = the same 145Ah available for recharging. With the lithium batteries having no restrictions to their charge rate all the way to 99%SOC and now losses as far as charging efficiency all the 145Ah will be returned to the battery.

What were the advantages gained by changing only the type of battery used:
Putting the weight, cycle life and useable capacity aside,
Unlimited for the general use pattern discharge capability without useable capacity loss
A gain of 25Ah useable without an alteration to the charging system
The ability to use all of the 400Ah capacity at any time chosen if required so not limited to waiting for a full sun day
No battery damage if the 100%SOC is not reached when recharging, no matter how long the use period. This give flexibility to the system, 300Ah could be used in one day and as long as the use did not exceed the recharging capability and day after that the system would still be fine, every bit of the days charging capacity not used would bring the battery capacity closer to the fully charged state

So, looking at Jon's example again, by increasing his solar capacity by 200w he gained 200 x 70% = 140w x 5 peak sun hrs = 700w = 58Ah of solar harvesting, 58 - 25 = 33Ah useable while the sun shines, but no improvement in system flexibility, his system still relies on the sun being available every day for the 5 peak sun hrs for any gain to be noticed.

I'm not saying you don't need a method of recharging the batteries equal to what you use, what I am saying is that the recharging can happen when it suits you and the recharging is available, the batteries do not dictate your lifestyle, they enhance it by making the stored capacity available when you want to use it.

Yeah, I know many of you will have rolled your eyes back about 20 paragraphs ago, but a stead reread and hopefully you will be able to absorb what I just one finger typed

T1 Terry